java - 存储数组中的数据以供以后比较

Question

我有一个程序，用户可以输入 4 个数字。输入所有数字后，将为用户提供四个值中的平均值、最低值和最高值。如果用户继续该程序，它会要求再输入 4 个值，并再次给出这四个值中的平均值、最低值和最高值。 (等等……)

但是，我似乎无法弄清楚如何比较给出的数组结果，以输出最低的最低值、最高的最高值以及每个 4 位数组的所有结果中给出的所有结果的平均值。

如果我需要更多解释，请告诉我。

*代码不完整

package example;

import java.util.*;

public class Example {

double highestValue;
double lowestValue;
public static void main(String[] args) {

System.out.println("Hello (Enter each digit when prompted)");
System.out.println();

Scanner input = new Scanner(System.in);

String yesOrNo = "y";
while (yesOrNo.equalsIgnoreCase("y")) {
    // Calls inputDigit and stores array in array storage variable
    double[] array = inputDigit(input, "Enter a number: ");

    displayFirst(array);            
    highestChecker(array);

    System.out.println();

    yesOrNo = askToContinue(input);
    System.out.println();

    System.out.println();

        if (yesOrNo.equalsIgnoreCase("n")) {
            System.out.println("done!);
            displayHighest(array);
        }
    }
}

public static double[] inputDigit(Scanner input, String prompt) {
// Creates a 4 spaced array
double[] array = new double[4];
    // For loop that stores each input by user
    for (int counter = 0; counter < array.length; counter++) {
        System.out.print(prompt);

        try {
            array[counter] = input.nextDouble();
            if (array[counter] <= 1000){
            } else if (array[counter] >= -100){
            } else {
                System.out.println("Error!\nEnter a number greater or equal to -100 and"
                        + "less or equal to 1000.");
            }
        } catch (InputMismatchException e){
            System.out.println("Error! Please enter a digit.");
            counter--; // This is designed to backup the counter so the correct variable can be input into the array
            input.next();
        }
    }
return array;
}

public static void displayFirst(double[] array){
    Arrays.sort(array);
    double highestValue = array[3];
    double lowestValue = array[0];
    double average = calculateAverage(array);
    System.out.println("RESULTS FOR CURRENT NUMBER CYCLE"
        + "\n--------------------------------"
        + "\nAverage Value - " + average
        + "\nHighest Value - " + highestValue
        + "\nLowest Value - " + lowestValue);
}

public static double[] highestChecker(double[] array){
    double[] arrayC = Arrays.copyOf(array, array.length);
    Arrays.sort(arrayC);
    double lowestChecked = arrayC[0];
    double highestChecked = arrayC[3];
    double highestAverage;
// Check lowest value

// Check highest value
return array;
}

public static void displayHighest(double[] array){
    Arrays.sort(array);
    double highestValue = array[0];
    double lowestValue = array[3];
    double average = calculateAverage(array);
    System.out.println("RESULTS FOR HIGHEST VALUE"
        + "\n-------------------------"
        + "\nHighest Average Value - " + average
        + "\nHighest Highest Value - " + highestValue
        + "\nHighest Lowest Value - " + lowestValue);
}

public static double calculateAverage(double[] array) {
    double sum = 0;
    double average;
       for (int i = 0; i < array.length; i++) {
            sum = sum + array[i];
}
average = (double)sum/array.length;
return average;
}

public static String askToContinue(Scanner input) {
    boolean loop = true;  
    String choice;
    System.out.print("Continue? (y/n): ");
do {
    choice = input.next();
    if (choice.equalsIgnoreCase("y") || choice.equalsIgnoreCase("n")) {
        System.out.println();
        loop = false;
    } else {
        System.out.print("Please type 'Y' or 'N': ");
    }
} while (loop);
return choice;
}
}

程序应该做什么的示例输出。

Enter a number: 2
Enter a number: 4
Enter a number: 6
Enter a number: 8
RESULTS FOR CURRENT NUMBER CYCLE
--------------------------------
Average Value - 5.0 // <-- This value should the highest average
Highest Value - 8.0
Lowest Value - 2.0

Continue? (y/n): y


Enter a number: 7
Enter a number: 5
Enter a number: 3
Enter a number: 1
RESULTS FOR CURRENT NUMBER CYCLE
--------------------------------
Average Value - 4.0
Highest Value - 7.0
Lowest Value - 1.0 // <-- This value should be the lowest, lowest value

Continue? (y/n): y


Enter a number: 9
Enter a number: 1
Enter a number: 4
Enter a number: 5
RESULTS FOR CURRENT NUMBER CYCLE
--------------------------------
Average Value - 4.75
Highest Value - 9.0 // <-- This value should be the highest, highest value
Lowest Value - 1.0 // <-- This value should be the lowest, lowest value

Continue? (y/n): n

You have exited the program. 
Thank you for your time.

这应该是最终结果。

RESULTS FOR HIGHEST VALUE
-------------------------
Highest Average Value - 5.0
Highest, Highest Value - 9.0
Lowest, Lowest Value - 1.0

Answer 1

要找到平均值，您可以使用 java-8

OptionalDouble average = Arrays.stream(array).average();

要找到最低和最高的元素，我们可以对其进行排序并使用:

// sort the array (default by ascending)
Arrays.sort(array);
double lowest = array[0]; 
double highest = array[array.length - 1];

由于数组已排序，第一个索引应该是最低 元素，最后一个是最高

---

编辑:

要找到整体的最低值和最高值，您可以定义两个静态变量:

static double highestValueOverAll = Double.MIN_VALUE;
static double lowestValueOverAll = Double.MAX_VALUE;

现在在 highestChecker() 中(可能重命名)

public static double[] highestChecker(double[] array) {

        // ...

        if (lowestChecked < lowestValueOverAll)
            lowestValueOverAll = lowestChecked;

        if (highestChecked > highestValueOverAll)
            highestValueOverAll = highestChecked;

        // ...
}

如果当前的最低/最高值小于/大于之前的值，我们只是进行简单的交换。 while-loop 完成后，您可以将其打印出来。

注意:数组也是对象，因此您不需要在每个方法中对它们进行排序。